Pulsating Heat Pipe Heatsink

Abstract

The invention relates to a pulsating heat pipe heat sink (10; 10a to 10h), with at least two fluidically separated channels (24; 24a; 24b; 24c; 24d, 26; 26a; 26b; 26c; 26d; 51 to 53; 61 to 64; 68, 69) for guiding a vaporizable cooling medium (A, B, C), with an evaporator area (16) for arranging at least one heat-generating component (1), and with a condenser area (22) spaced apart from the evaporator area (16).

Description

Technical field

[0001] The invention relates to a pulsating heat pipe heat sink which is characterized by a particularly advantageous cooling behavior of at least one heat-generating component. State of the art

[0002] From DE 10 2021 204 769 A1 of the applicant, a pulsating heat pipe heat sink with the features of the preamble of claim 1 is known. The known heat sink is characterized essentially by having two separate channels arranged side by side in one plane for guiding a cooling medium. A heat-generating component arranged in an evaporator area and thermally connected to the heat sink is thus cooled simultaneously by both channels. The use of two fluidically separated channels has the particular advantage that even if one channel fails or leaks due to the escape of cooling medium, the functionality of the heat sink is at least partially maintained. Disclosure of the invention

[0003] The pulsating heat pipe heat sink according to the invention, with the features of claim 1, has the advantage that different operating points of the cooling media can be generated in the at least two channels. This has the advantage that, for example, the channel containing a first cooling medium is already at its operating point, i.e., evaporates, while the channel with the second cooling medium only reaches its operating point at higher temperatures. This has the advantage, for example, that the first cooling medium can exhibit very good start-up behavior, while the second cooling medium has the ability to transport very high heat values ​​to the condenser area. Because the first cooling medium evaporates early, it also improves the start-up behavior of the second cooling medium, since the latter is already (uniformly) preheated by the channel containing the first cooling medium.Furthermore, the advantage is that the first cooling medium, which is sensitive to temperature fluctuations, can compensate for potential temperature fluctuations in the second cooling medium. Additionally, instabilities that may occur in the temperature profile of the two channels are balanced out by their independent operation. If one channel is unstable, the other can dissipate more heat directly, thus smoothing out temperature peaks. The aforementioned advantages are further enhanced by an optimal selection of the geometric cross-sections of the channels.

[0004] In light of the above explanations, a pulsating heat pipe heat sink according to the invention, comprising the features of claim 1, therefore has at least two fluidically separated channels for guiding a vaporizable cooling medium. Furthermore, an evaporator section for accommodating at least one heat-generating component and a condenser section arranged at a distance from the evaporator section are provided. Crucially, cooling media with different operating points are arranged in the at least two channels, from which the respective cooling medium in the evaporator section can be vaporized by heat input from the at least one heat-generating component.

[0005] Advantageous further developments of the Pulsating Heat Pipe cooling body according to the invention are listed in the dependent claims.

[0006] Regarding the selection of different cooling media to achieve the different operating points, there are several possibilities: In a first variant, it is provided that the cooling media consist of at least two different chemical substances with different boiling points.

[0007] Alternatively, it can also be provided that the cooling media each consist of at least two identical chemical substances with different boiling points, and that the mixing ratio of the at least two substances in the cooling media is different. In other words, this means that different boiling points can be achieved by choosing different mixing ratios of the otherwise identical substances.

[0008] In yet another alternative embodiment, the cooling media arranged in the at least two channels may have different fill levels in those channels. This applies both to the use of the same cooling medium and to the use of different cooling media. In other words, even if the substances are the same or have the same boiling points, in a channel containing less cooling medium than another channel, more cooling medium evaporates due to the larger internal surface area of ​​the bubbles in the latter channel. This results in a different pressure gradient between the evaporator and condenser sections of the latter channel, and thus different flow conditions. This is primarily caused by the larger quantity or mass of the cooling medium to be heated in the latter channel.

[0009] There are also different possibilities regarding the arrangement of the at least two channels to the evaporator area, which produce different properties depending on the operating point: In one variant, the at least two channels are arranged in a single plane, at least in the evaporator area. This allows, for example, a relatively simple design for the heat sink or a very compact design in terms of height.

[0010] Alternatively, the at least two channels can be arranged on at least two levels, at least in the evaporator area. This way, heat input into a channel further away from the evaporator area is delayed, or the temperature rise in the channel closer to the evaporator area occurs more rapidly.

[0011] Alternatively or additionally to arranging the channels on one or different levels, it can be provided that the at least two channels, at least in the evaporator section, have different cross-sectional shapes and / or different cross-sectional sizes. This means, for example, that round, triangular, or rectangular channels, possibly with different cross-sectional sizes, influence the operating point. The effect of this design, when using the same cooling media, is comparable to that of different fill levels.

[0012] Alternatively, it can also be provided that at least two channels have the same cross-sections.

[0013] Regardless of the geometry or cross-section of the individual channels, a further advantageous embodiment of the cooling element provides that the at least two channels are designed in a meandering shape. In particular, it is provided that the at least two channels have channel sections arranged parallel to each other, at least in the evaporator area. This also includes the case where the at least two channels are intertwined, i.e., arranged alternately perpendicular to the longitudinal direction of the channel sections, at least in the evaporator area.

[0014] In an alternative design, it can also be provided that the at least two channels interlock in a comb-like manner, at least in the evaporator area.

[0015] It is also conceivable that at least two channels, at least in the evaporator area, are arranged at an oblique angle to each other.

[0016] However, it is also conceivable that at least the two channels, at least in the evaporator area, are designed in a star-shaped or cloverleaf shape without mutual or with mutual geometric overlap.

[0017] Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments of the invention and from the drawings. Brief description of the drawings Fig. Figure 1 shows a section through a first pulsating heat pipe heat sink according to the invention, Fig. 2 and Fig. 3 different cross-sections through the heat sink according to Fig. 1 in level II-II of the Fig. 1, Fig. 4 a section through a second heat sink according to the invention, Fig. 5 and Fig. 6 different cross-sections through the heat sink according to the Fig. 4 in level VV of the Fig. 4, Fig. 7 and Fig. 8 different cross-sections through the heat sink according to the Fig. 4 in level VII-VII of the Fig. 4, Fig. 9 a section through a third cooling body designed according to the invention, Fig. 10 to Fig. 14 different cross-sections through the heat sink according to the Fig. 9 in level XX of the Fig. 9, Fig. 15 a section through a fourth cooling body designed according to the invention with channels arranged at an oblique angle to each other, Fig. 16 a section through a fifth cooling body designed according to the invention with comb-like interlocking channels, Fig. 17 to Fig. 19 different cross-sections through the heat sink according to the Fig. 16 in level XVII-XVII of the Fig. 16, Fig. 20 a section through a sixth cooling body designed according to the invention with three fluidically separated channels, Fig. 21 and Fig. 22 a section in the XXI-XXI plane of the Fig. 20, Fig. 23 a section through a seventh cooling element designed according to the invention and Fig. 24 and Fig. 25 sections each through modified heat sinks with channels arranged in a star shape. Embodiments of the invention

[0018] Identical elements or elements with the same function are provided with the same reference numbers in the figures.

[0019] In the Fig. Figure 1 shows a section through a first pulsating heat pipe heat sink 10 designed according to the invention, hereinafter referred to simply as heat sink 10. The heat sink 10 serves to cool at least one component, located only in the Fig. 2 and Fig. 3. A recognizable component 1 or assembly, wherein the component 1 or assembly dissipates heat during operation. The component 1 or assembly can be, for example, but is not limited to, a power IC, a power transistor, or the like. The heat sink 10 is preferably used in the context of electromobility or in a vehicle capable of at least partial autonomy. However, the use of the heat sink 10 should not be limited to such applications.

[0020] The heat sink 10 has a cuboid-shaped housing 12, which is made of metal and can be constructed in one or more parts. Regarding the manufacturing process of the housing 12 or the heat sink 10, it can be produced by either machining or non-machining processes. It is also conceivable to manufacture the heat sink 10 using an additive manufacturing process.

[0021] In the exemplary embodiment, the housing 12, which has a rectangular basic shape, has through-openings 14 in its corner areas, which serve to attach the heat sink 10 to a larger support assembly or similar.

[0022] The at least one heat-generating component 1 is arranged in the area of ​​an evaporator area 16, which is shown in the illustration of the Fig. 1 has a square base and is characterized by a boundary 18. The evaporator area 16 is shown in the illustration of the Fig. 2 and Fig. 3 is shown in relief only for better visibility, but runs on the surface of the housing 12. The evaporator area 16 is surrounded by a rectangular intermediate area 20 with a boundary 21, which in turn is surrounded by a rectangular or frame-shaped condenser area 22 with a boundary 23.

[0023] Within the cross-section of the housing 12, two fluidically separated channels 24 and 26 are provided as an example. The two channels 24 and 26 extend at least from the evaporator section 16 to the condenser section 22. On opposite sides of the housing 12, the two channels 24 and 26 can each be filled with a cooling medium A (first channel 24) and a cooling medium B (second channel 26) via a supply channel 28 and 30, respectively. Furthermore, the two supply channels 28 and 30 can be sealed to prevent the respective cooling medium A and B from escaping the channels 24 and 26 during operation of the heat sink 10.

[0024] It is essential that the two cooling media A and B have different boiling points or operating points. This can be achieved by using different (chemical) substances for the two cooling media A and B, or by using the same substances but in different mixing ratios. Finally, it is also possible for the two cooling media A and B to consist of the same (chemical) substances and have the same mixing ratio, but to be present in different fill levels within channels 24 and 26. This means that, for example, with the same volume in both channels 24 and 26, cooling medium A (in its liquid state) occupies only 40% of the volume of channel 24, while cooling medium B occupies a larger volume, for example, 70%, of the volume of channel 26.

[0025] The operating principle of the heat sink 10, which is known per se, is explained below as follows: when the at least one heat-generating component 1 is operated, the cooling medium A, B located in the channels 24, 26 is heated above its boiling point, whereupon it evaporates and, with the formation of vapor bubbles, flows towards the condenser section 22. There, the cooling medium A, B condenses again and can thus flow back into the evaporator section 16. Because the two cooling media A, B have different boiling points or operating points, the two cooling media A, B evaporate at different temperatures (assuming the same heat input into the respective cooling medium A, B).

[0026] In the illustrated embodiment, the two channels 24, 26 are each meandering and each has first channel sections 31 (first channel 24) and first channel sections 32 (second channel 26) arranged parallel to each other. The straight first channel sections 31, 32 are each equidistant from each other a1 and a2 ( Fig. 2) and, moreover, have at least substantially the same length when viewed longitudinally in the first channel sections 31, 32. Two immediately adjacent first channel sections 31, 32 of the respective channel 24, 26 are connected to each other by means of arc-shaped second channel sections 33, 34. Furthermore, the two outermost first channel sections 31, 32 of the two channels 24, 26 are connected to each other via a return section 36, 38, into which the respective supply channel 28, 30 also flows.

[0027] In the Fig. 2 and Fig. Figure 3 shows that the first channel sections 31, 32 run in two planes 41, 42 arranged one above the other in a direction perpendicular to the plane of the evaporator area 16. In the embodiment according to the Fig. 2. The cross-sections of the first channel sections 31 are square, while the cross-sections of the first channel sections 32 are rectangular. Furthermore, the first channel sections 31 and 32 extend at the same distance from the underside 43 and the topside 44 of the housing 12, respectively.

[0028] In the Fig. In the embodiment shown in Figure 3, the first channel sections 31 of the first channel 24 each have a circular cross-section, while the first channel sections 32 of the second channel 26 each have a triangular cross-section. The size of the cross-sections of the two channels 24, 26, or of the respective first channel sections 31, 32, can be the same or different, depending on the cooling medium A, B.

[0029] The one in Fig. The heat sink 10a shown in section 4 differs from the heat sink 10 essentially in that its two channels 24a, 26a are intertwined in the area of ​​the first channel sections 31a, 32a. This is particularly evident from the Fig. 5 can be seen where two immediately adjacent first channel sections 31a, 32a are arranged alternately on different levels 41, 42.

[0030] In the Fig. In contrast, an embodiment is shown in which two first channel sections 31a, 32a of each channel 24a, 26a arranged directly next to each other have alternately different cross-sections, in the exemplary embodiment alternating a square and a rectangular cross-section.

[0031] In the Fig. 7 and Fig. Figure 8 shows the transition between the first channel sections 31a, 32a, each having a square cross-section, between levels 41, 42 in the area of ​​the second channel sections 33a, 34a. Fig. 7 It is particularly evident that the first two channel sections 31a, 32a are each connected by a diagonally running connecting section 45 as the second channel section 33a, 34a, while in the Fig. Figure 8 shows an embodiment in which the two first channel sections 31a, 32a are connected to each other by means of a step-shaped connecting section 46 as the second channel section 33a, 34a.

[0032] The one in Fig. The heat sink 10b shown in Figure 9 is characterized by the fact that its two channels 24b, 26b are arranged laterally offset from each other in the region of the first channel sections 31b, 32b, such that in the region of the first channel sections 31a, 32a, there is no overlap between the first channel sections 31b, 32b in a direction perpendicular to the longitudinal extent of the first channel sections 31b, 32b, or rather, gaps 47 are present between the first channel sections 31b, 32b. Various arrangements of the first channel sections 31b, 32b are possible, which are described below. Fig. 10 to 14 are described as follows:

[0033] In the embodiment according to the Fig. 10. The first channel sections 31b, 32b run completely in different planes 41b, 42b. For example, the first channel sections 31b have a rectangular cross-section, while the first channel sections 32b are each square.

[0034] In the Fig. 11 The two levels 41b, 42b partially overlap each other, such that in an intermediate zone 48 both first channel sections 31b and first channel sections 32b are present.

[0035] In contrast, in the Fig. 12 the case is shown that the first channel sections 31b on the side facing the evaporator area 16 have the same distance to the evaporator area 16 as the first channel sections 32b.

[0036] In the Fig. Figure 13 illustrates the case where the first channel sections 31b, 32b of immediately adjacent first channel sections 31b, 32b are arranged alternately on different levels 41b, 42b. However, the first channel sections 31b, 32b each have the same cross-section when considered individually.

[0037] In contrast, in the Fig. Figure 14 shows the case in which the first channel sections 41b, 42b additionally have alternating rectangular and square cross-sections in the different planes 41b, 42b, so that in plane 41b rectangular first channel sections 31b, 32b are arranged next to each other, and in plane 42b first channel sections 31b, 32b with square cross-sections are arranged next to each other.

[0038] In the Fig. Figure 15 shows a heat sink 10c in which its channels 24c, 26c, arranged on different planes, have first channel sections 31c, 32c that are arranged at an oblique angle α to each other. In the illustrated embodiment, the angle α is approximately 60°, but it can typically be between approximately 20° and 90°. It is further shown, purely by way of example, that the first channel 24c, which has a smaller cross-section, runs completely above the second channel 26c, which has a larger cross-section.

[0039] The heat sink 10d according to the Fig. Figure 16 has two channels 24d, 26d, which are comb-like and interlock in the region of their first channel sections 31d, 32d. By way of example, the first channel sections 31d are closer together than the first channel sections 32d. Furthermore, the first channel sections 31d have a larger cross-section than the first channel sections 32d.

[0040] In the Fig. Figures 17 to 19 show different arrangements of the first channel sections 31d and 32d. While in the Fig. 17 the first channel sections 31d, 32d to the evaporator area 16 have the same distance or run in the same plane, it is the case that Fig. 18 provides that the first channel sections 31d, 32d are arranged on different levels 41d, 42d and thus have a different distance to the evaporator area 16. According to the Fig. 19 It is also conceivable that the first channel sections 31d, 32d of immediately adjacent first channel sections 31d, 32d run on different levels 41d, 42d.

[0041] The one in Fig. In contrast to the cooling elements 10, 10a to 10d, the illustrated cooling element 10e has three fluidically separated channels 51, 52 and 53. For example, the three channels 51, 52, 53 are each meandering and interlock like a comb. The three channels 51, 52, 53, whose cooling media A, B and C have different boiling points or operating points, can either be arranged on a common plane ( Fig. 21), or at different levels according to the representation of the Fig. 22.

[0042] The one in Fig. The cooling element 10f shown in Figure 23 has four fluidically separated channels 61, 62, 63, and 64 for cooling media with different operating points, wherein the individual channels 61, 62, 63, and 64 have a different number of first channel sections 65, 66, and 67. The first channel 61 has a total of ten first channel sections 65, which are arranged in a meandering pattern relative to each other. In contrast, the oval-shaped second channel 62 has only two first channel sections 66 arranged parallel to each other, which traverse the evaporator area 16 centrally. The identically designed channels 63 and 64 each have only one first channel section 67, which runs opposite each other along the edge regions of the evaporator area 16.

[0043] The one in Fig. The heat sink 10g shown in Figure 24 has two star- or cloverleaf-shaped channels 68, 69 for cooling media with different operating points, arranged one above the other in different planes, with the evaporator area 16 located in a centrally arranged overlapping area of ​​the channels 68, 69. In contrast, the heat sink 10h, according to the Fig. 25 also shows two channels 68, 69, which, however, since they have no overlap area, are arranged in a common plane.

[0044] The heat sink 10, 10a to 10h described so far can be modified or adapted in a variety of ways without deviating from the inventive concept. For example, it is conceivable to assign components 1 with different heat outputs or maximum temperatures to different channels or cooling media in a targeted manner, or to arrange them in their area, in order to enable specifically adapted cooling of different components 1. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2021 204 769 A1

[0002]

Claims

Pulsating heat pipe heat sink (10; 10a to 10h), with at least two fluidically separated channels (24; 24a; 24b; 24c; 24d, 26; 26a; 26b; 26c; 26d; 51 to 53; 61 to 64; 68, 69) for guiding a vaporizable cooling medium (A, B, C), with an evaporator section (16) for arranging at least one heat-generating component (1), and with a condenser section (22) arranged at a distance from the evaporator section (16), characterized in that the at least two channels (24; 24a; 24b; 24c; 24d, 26; 26a; 26b; 26c; 26d; 51 to 53; 61 to 64; 68, 69) arranged cooling media (A, B, C) have different operating points from which the respective cooling medium (A, B, C) can be evaporated in the evaporator area (16) by heat input from the at least one heat-generating component (1). Cooling element according to claim 1, characterized in that the cooling media (A, B, C) consist of at least two different substances with different boiling points. Cooling element according to claim 1, characterized in that the cooling media (A, B, C) each consist of at least two identical substances with different boiling points, and that the mixing ratio of the at least two substances in the cooling media (A, B, C) is different. Cooling sink according to one of claims 1 to 3, characterized in that the cooling media (A, B, C) arranged in the at least two channels (24; 24a; 24b; 24c; 24d 26; 26a; 26b; 26c; 26d; 51 to 53; 61 to 64; 68, 69) have a different degree of filling in the at least two channels (24; 24a; 24b; 24c; 24d, 26; 26a; 26b; 26c; 26d; 51 to 53; 61 to 64; 68, 69). Cooling sink according to one of claims 1 to 4, characterized in that the at least two channels (24b; 24d, 26b; 26d; 51 to 53; 61 to 64; 68, 69) are arranged at least in the evaporator area (16) in the area of ​​a single plane. Cooling sink according to one of claims 1 to 4, characterized in that the at least two channels (24; 24a; 24b; 24c; 24d, 26; 26a; 26b; 26c; 26d; 51 to 53; 68, 69) are arranged at least in the evaporator area (16) on at least two different levels (41; 41b; 41d, 42; 42b; 42d) with different distances to the evaporator area (16). Cooling sink according to one of claims 1 to 6, characterized in that the at least two channels (24; 24a; 24b; 24c; 24d, 26; 26a; 26b; 26c; 26d; 51 to 53; 61 to 64; 68, 69) have different cross-sectional shapes and / or different cross-sectional sizes at least in the evaporator area (16). Heat sink according to one of claims 1 to 6, characterized in that the at least two channels (24; 24a; 24b; 24c; 24d, 26; 26a; 26b; 26c; 26d; 51 to 53; 61 to 64; 68, 69) have the same cross-sections. Cooling sink according to one of claims 1 to 8, characterized in that the at least two channels (24; 24a; 24b; 24c; 24d, 26; 26a; 26b; 26c; 26d; 51 to 53; 61 to 64) are meander-shaped. Cooling sink according to claim 9, characterized in that the at least two channels (24; 24a; 24b; 24c; 24d, 26; 26a; 26b; 26c; 26d; 51 to 53; 61 to 64) have at least in the evaporator area (16) first channel sections (31; 31a to 31d, 32; 32a to 32d; 65, 66) which are arranged parallel to each other. Cooling sink according to claim 10, characterized in that the at least two channels (24; 24a; 24b; 24c; 24d, 26; 26a; 26b; 26c; 26d) are intertwined at least in the evaporator area (16). Cooling sink according to claim 10, characterized in that the at least two channels (24d, 26d; 51 to 53; 61 to 64) interlock in a comb-like manner at least in the evaporator area (14). Cooling sink according to claim 9, characterized in that the at least two channels (24c, 26c) have first channel sections (31c, 32c) at least in the evaporator area (16) which are arranged at an oblique angle (α) to each other. Cooling sink according to claim 9, characterized in that the at least two channels (68, 69) are formed in a star shape without mutual geometric overlap, at least in the evaporator area (16). Cooling sink according to claim 9, characterized in that the at least two channels (68, 69) are designed in a star shape with mutual geometric overlap, at least in the evaporator area (16).

Images